I've now heard the stat "Of teams tied 2-2 after four games, the team who wins the fifth game in a best of seven series in the NBA will win the series 80% of the time."

Okay, first, a team who is up three games to two, if both teams are completely even, should win 75%. So let's see if the extra 5% can be made up for in the fact that the fifth game's home team is the team with home court advantage in the series, which usually means they're better to begin with. Or just the psychological advantage of pressuring the other team with elimination.